The present invention relates to connecting assemblies between two components, at a driveshaft. In particular, the invention concerns a connecting assembly between an outer joint part of a constant velocity joint of a driveshaft and a wheel hub or a shaft flange in the driveline of a motor vehicle.
From DE 197 51 855 C1 there is known a connecting assembly of a first type having an end toothing at an outer joint part at the wheel hub end of a constant velocity joint of the driveshaft, and having an end toothing at the wheel hub. The end toothings are axially inserted into one another and engage one another in a clearance-free way in the circumferential direction. Also, the teeth of the end toothings each include radially outwardly opening circumferential grooves which are delimited by two flanks and which, together, form a circumferentially extending annular groove. The annular groove, on the outside, is engaged by a securing ring. At the wheel hub and at the outer joint part there are also formed concentric annular cylindrical projections with approximately identical diameters. From this reference, there is also known a connecting assembly of a second type having an end toothing at an outer joint part at a shaft flange end of a driveshaft, and having an end toothing at the shaft flange. The end toothings are axially inserted into one another and engage one another in a clearance-free way in the circumferential direction. Also, the teeth of the end toothings are provided with radially outwardly opening circumferential grooves which are delimited by two flanks and which, together, form a circumferentially extending annular groove. The annular groove, on the outside, is engaged by a securing ring. At the shaft flange and at the outer joint part there are also formed concentric annular cylindrical projections with approximately identical diameters. These assemblies meet all the requirements regarding a clearance-free connection which can easily be assembled, but the end toothings cannot easily be produced in the required quality.
U.S. Pat. No. 967,395 proposes a claw coupling between two rotating hollow shafts. The individual claws include inner grooves which, in the engaged condition, form a continuous groove in whose inside there is positioned a retaining ring. This type of coupling is not suitable for connecting annular parts with intermediate walls or inserts because it is necessary to ensure access for fitting the retaining ring through the inside of the hollow shafts.
DE 8136172 U1 proposes a coupling for rigidly connecting coaxial components in the case of driveshafts. The components to be connected are provided with end toothings which are inserted into one another. For the purpose of being axially secured, the components to be connected are provided with a backwardly extending shaft step which is arranged behind the end toothing. In the engaged condition of the end toothings, pieces with a U-profile in the form of circular segments are placed on to the circumference of the shaft steps. To prevent the U-profile pieces from being released, they have to be joined to form a ring, or they have to be secured by a slid-on ring, or they have to be clamped relative to one another by wedges. This results in very complicated assembly procedures.
From DE 196 45 880 A1, there is known a connecting assembly between an outer joint part of a constant velocity joint and the shaft flange of a driveshaft wherein, for the purpose of transmitting torque, the two parts, in the direction of rotation, engage one another in a clearance-free way via inter-engaging claw toothings. At the outer joint part, the front ends of the claws form an assembled planar end face which is supported against an assembled planar end face at the shaft flange between the base regions of the claws. At the ends of the claws of the two parts there are provided outwardly pointing pawls. At each of the parts, the pawls form an assembled annular collar with a backwardly pointing conical inclined face. To ensure that the abutting planar end faces of the two parts are axially clamped together in a clearance-free way, a securing ring is inserted between the annular collars composed of the pawls, which securing ring rests on the conical inclined faces. In addition to the inclined faces and the flank faces of the teeth of the claw toothings, it is necessary for the planar end faces to be machined accurately to achieve a clearance-free, torque transmitting connection.
From DE 27 15 639 B1 and DE 25 54 574 A1 there are known flange connection assemblies at shaft parts of universal joints, which assemblies, at two annular flange parts, each include two groups of parallel grooves. The groups are aligned at an angle relative to one another. The grooves are provided in a larger number of the type of precision toothings.
Connecting assemblies of the foregoing type are also described in the earlier unpublished application DE 199 58 674.8 and have an end toothing at a first component and an end toothing at a further component, wherein the end toothings include teeth and gaps which are axially inserted into one another and, in the circumferential direction, engage one another in a clearance-free way. The teeth of the end toothings, at the outer circumference, include outwardly opening circumferential grooves which are delimited by two flanks and which, when the end toothings are inserted into one another, form a circumferentially extending annular groove. The annular groove, on the outside, contains a securing ring. The teeth at the two components, i.e. at the first component and at the further component, are arranged within an imaginary cylindrical annular space. The gaps, in pairs, are positioned in two groups of continuous imaginary groove tracks which are arranged at a right angle relative to one another and which twice pass through the respective cylindrical annular space.
Accordingly, there is a need for a connecting assembly between an outer joint part of a constant velocity joint of a driveshaft and another part, having improved manufacturability.
It is an object of the present invention to provide a connecting assembly between an outer joint part of a constant velocity joint of a driveshaft and a further component, for example a wheel hub or a shaft flange, which can be provided more easily and cost-effectively than conventional connecting assemblies.
An improved connecting assembly is provided wherein, in an end view, the images of the teeth and gaps are the same at both components, i.e. at the outer joint part and the further component. In addition, starting from the corresponding images of the teeth and gaps at both components, matching complementary images of the teeth and gaps at the two components result when the components are rotated relative to one another by 90xc2x0 or 180xc2x0.
A further solution is provided wherein, at, the cylindrical annular space, the ratio of the inner diameter (d) to the outer diameter (D) is defined by: d{square root over (2)}xe2x89xa7xe2x89xa7D, wherein, when the number (z) of teeth and gaps, the width (t) of the teeth and of the gaps is given by: t={square root over (2(D/2z))}.
According to another solution, in an axial view, the image of the teeth and gaps comprises a first axis of symmetry which extends through the central axis of the cylindrical space and intersects two teeth positioned opposite one another in pairs. A second axis of symmetry extends perpendicularly relative to the first axis of symmetry through the central axis and intersects two gaps positioned opposite one another in pairs.
According to yet a further solution, in an axial view, the image of the teeth and gaps comprises a first axis of symmetry which extends through the central axis of the cylindrical space. On the first axis of symmetry, at least two teeth positioned opposite one another can be mirrored on two identically shaped gaps positioned opposite one another. A second axis of symmetry extends perpendicularly relative to the first axis of symmetry through the central plane. On the second axis of symmetry, at least two teeth positioned opposite one another can be mirrored on two identically shaped gaps positioned opposite one another. A third axis of symmetry extends through a tooth and a gap positioned radially opposite one another, and halves the angle between the first and the second axis of symmetry. On the third axis of symmetry, teeth can be mirrored on identically shaped teeth, and gaps can be mirrored on identically shaped gaps.
The above arrangements result in advantageous, corresponding embodiments of the toothing elements at both components, which simplify production.
According to a first embodiment, the gaps in each of the annular cylinders are formed by a group of three or five groove tracks and another group of two or four groove tracks. Corner teeth in the form of four angle pieces are offset relative to the bisectrix in such a way that they do not obstruct the toothing engagement. This results in toothing geometries permitting relatively straight-forward machining operations.
The toothings are preferably produced by using a broaching tool moving transversely to the longitudinal axis of the annular cylinders for forming the groove tracks, which form the toothing gaps, into the originally solid annular cylinders. For each annular cylinder, two different broaching tools are used, with the workpiece being re-clamped once. In particular, it is rotated by 90xc2x0 around its axis. The imaginary groove tracks corresponding to the travel of the broaching tools and, thus, the gaps are symmetrical relative to two radial planes which extend through the longitudinal axis and are positioned perpendicularly relative to one another.
The first broaching tool may include an uneven number of three or five parallel broaching needles clamped relative to one another, whereas the second broaching tool can include a corresponding even number of four or six parallel broaching needles which are supported relative to one another or clamped relative to one another. The latter are positioned in such a way that in the region of the bisectrix between the two radial reference planes, two rectangularly delimited angle pieces are produced at the components by broaching in two directions extending perpendicularly relative to one another, which two angle pieces do not obstruct one another during assembly.
According to a second embodiment, the gaps in each of the annular cylinders are formed by a group of three or five groove tracks. Two corner teeth, each in the form of angle pieces, are offset relative to one of the bisectrices in such a way that they do not obstruct the engagement of the toothings. A corner gap is diametrically opposed to a further corner tooth on the other one of the bisectrices, so that a suitable tooth engagement takes place when the components are rotated relative to one another by 180xc2x0.
Again, the toothings are produced by using a broaching tool moving transversely to the longitudinal axis for forming the groove tracks, which form the toothing gaps, into the annular cylinders. One single broaching tool is sufficient for producing all of the groove tracks in the two components. The imaginary groove tracks corresponding to the travel of the broaching tools and thus the gaps are asymmetrical relative to two radial planes which extend through the longitudinal axis, and are positioned perpendicularly relative to one another.
The broaching tool can include three or five broaching needles which are clamped relative to one another. With this method of production, too, three corner pieces and the one corner gap are produced entirely by broaching the continuous groove tracks in the annular cylinders.
The inventive connecting assemblies are advantageous in that they can be assembled quickly and easily. As a result of the very short displacement paths when inserting the end toothings into one another, driveshafts can be fitted and removed very easily between the wheel hub and shaft flange of a differential drive, especially in a complete vehicle with a finish-assembled wheel suspension system. This is advantageous for both the initial assembly procedures and for subsequent repairs. Furthermore, the connecting assemblies are characterised by a small number of parts and a low weight. The circumferential grooves for the connecting securing ring can either be formed on each of the parts individually or, in the case of inter-engaging end toothings, on both parts simultaneously.
Any torque which has to be transmitted by the driveshaft will be accommodated by the inter-engaging end toothings of the connecting assembly. Any rotating bending moments at the connecting assembly, which originate from the constant velocity joint rotating in an articulated condition, primarily act on the securing ring positioned in the annular groove. In each circumferential groove, one flank of the securing ring is subjected to load, with the load being removed from the other flank. As far as circumferentially directly adjoining circumferential grooves are concerned which are each associated with a different tooth and thus with another one of the two end toothings, it is the flanks pointing in opposite directions which are loaded by the securing ring.
According to a first advantageous design, the toothing elements of the two end toothings comprise flanks which extend parallel to the radial planes. This results in a simple geometry that is easy to produce.
As a result of the axial displaceability of such end toothings, the securing ring and the circumferential grooves are designed in such a way that the former, by means of both flanks, is supported on the latter in a clearance-free way in order to be able to accommodate axial forces in both directions without there occurring any axial displacements when the direction of load application changes.
According to a further advantageous design, the toothing elements of the two end toothings comprise flanks which enclose an angle with the radial planes, with the angles of the flanks at the two end toothings opening in opposite directions and being of identical size. The teeth of the two end toothings are thus wedge-shaped and can be inserted into one another in a clearance-free way. The wide tooth bases provide an increase in strength and ensure a uniform load distribution in the teeth.
In the case of such end toothings with teeth whose flanks enclose an angle, axial support of the parts is secured in one direction (pressure). Thus, the securing ring and the circumferential grooves can be designed in such a way that clearance-free contact of the securing ring at the flanks of the grooves takes place in the opposite direction only (tension). The circumferential grooves of the one end toothing can be offset relative to the circumferential grooves of the other end toothing in such a way that there is formed an annular groove extending to and fro. This results in the flanks of the securing ring only coming into contact with those flanks of the circumferential grooves which face the respective other end toothing. A first embodiment, at the outside of the end toothings, comprises circumferential grooves with parallel flanks, with the securing ring comprising corresponding parallel flanks. The circumferential grooves are easy to produce, and it is possible to use standard securing rings.
According to a different embodiment, the flanks of the circumferential grooves, on the outside of the two end toothings, enclose an angle relative to an imaginary axis-normal radial plane, which angle opens radially outwardly. The securing ring comprises corresponding flanks which enclose the same angle relative to an imaginary axis-normal radial plane. In the inserted condition of the end toothings, the circumferential grooves thus form a wedge-shaped groove which receives a securing ring with a wedge-shaped profile. The securing ring, as a result of its radial tensioning force, is pressed into the wedge-shaped groove, with axial force components occurring due to the wedge shape of the securing ring.
As a result of the interplay with a wedge shape of the end toothings, and due to the wedge-shaped profile of the securing ring and of the circumferential grooves, which form an annular groove extending to and fro, it is possible to generate an axial force component which, in the final analysis, presses the two end toothings into one another. In this way, it is possible to avoid any axial play and also any circumferential play in the connecting assembly.
Preferred embodiments of the invention are illustrated in the drawings and will be described below. Other advantages and features of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.